As is generally known, potassium chloride occurs as sylvite. The compound is also known as muriate of potash and can be extracted from salt water. Further methodology to synthesize the compound is by crystallization from solution, electrostatic separation from suitable minerals or flotation.
Other methods for forming potassium chloride include the preparation from solid ore. The ore is exposed to solution stripping and multi-element crystallization. Generally the stripping solution from the rejected liquid, salt and water generated in processing carnallite is selectively stripped the from the solid potassium salt ore to obtain halogen liquid. The liquid is rich in potassium chloride which is subsequently crystallized.
There are innumerable other methods to achieve synthesis, however, these are typically limited in the same manner; expensive unit operations and the inability of the product to be stored without significant moisture absorption.
Kali and Salz Aktiengesellschaft patented a method for manufacturing potassium chloride having a high potassium oxide content (55 wt.%) . The precursor was the fine salt resulting from the degradation of carnallite In the process alkyl amine salts are used as conditioning agents and flotation media containing magnesium and potassium chloride are used to separate this fine decomposition salt in an initial flotation stage into a grain size fraction of less than 0.1 mm as a first concentrate and a residue having a grain size of more than 0.315 mm. Subsequent to auxiliary conditioning , the residue is again floated and the potassium chloride surfaces as a second concentrate. The potassium chloride is separated from the mixture without any further conditioning in another flotation stage, and collected.
Ferguson et al., in United States Patent Publication 2005/0036929, published Feb. 17, 2005, disclose an apparatus and method for the production of a compacted potassium chloride granule Essentially, the method includes the use of sodium hexametaphosphate as a binder which is added to the potassium chloride feedstock. The binder is indicated to sequester moisture.
In U.S. Pat. No. 5,503,641, issued Apr. 2, 1996, to Bakardjiev et. al., there is disclosed a process for synthesizing potassium chloride where a multitude of unit operations are required to effect the result. Many of the operations are involved and require high energy expenditures.
Having regard to the fact that potassium chloride crystals are very high energy and high stress, dendrites can form between crystals when the same are stored in conditions having relative humidity of greater than approximately 70%. In this manner, the material must be purchased and immediately used in order to avoid particle accretion.
It would be desirable to have a process where the unit operations were minimized with a low energy requirement with the resulting product being resistant to moisture absorption.
The present invention satisfies these goals.